The only real usefulness I've ever found is following musical artists to keep up with what they're putting out, but with Mastadon I've been using it as something of a news source and getting a lot out of it
It's only really useful for aggregation of PSAs (in my opinion) and I don't need to be on one of those sites since if it's important enough someone will repost the tweet to a platform I use, or it will get reposted in a "news" article. In other news though, I also find it horribly annoying when I click on a news article to discover that it's just screenshots of a bunch of tweets.